Low profile water distiller

ABSTRACT

A low profile water distiller has a housing. A steam chamber is located within the housing having a horizontal dimension greater than its vertical height. A condenser is also located within the housing having a horizontal dimension greater than its vertical height. The vertical height of the condenser is generally the same as the vertical height of the steam chamber. A raw water conduit extends in a generally horizontal plane within the housing for delivering water to be distilled into the steam chamber. A steam conduit also extends within the housing for delivering steam from the steam chamber to the condenser. The steam conduit extends in a generally horizontal plane parallel to the generally horizontal plane of the raw water conduit. An air circulation channel within the housing draws cooling air through the condenser in a generally horizontal path parallel to the generally horizontal planes of the raw water conduit and the steam conduit.

This is a continuation of copending application Ser. No. 07/642,790filed on Jan. 18, 1991, now U.S. Pat. No. 5,110,419.

FIELD OF THE INVENTION

The invention relates to water distillers and related control systems.

BACKGROUND OF THE INVENTION

It is well known that water supplied to households from some wells andcommunity water supplies often tastes unpleasant or is dangerous todrink because of minerals, chemicals, organisms and organic materialsthat are dissolved or suspended in the water. Widespread recognition ofthis information accounts for the variety of domestic water purificationdevices that have been developed and patented. However, use of waterpurifiers in homes is not as widespread as one would expect in view ofthe scope of the problem.

Most water distillers developed for home use have an electric heatingelement immersed in raw (that is, undistilled) water that is supplied toa boiler-evaporator from the water mains of a dwelling. The mass ofwater in the boiler is raised to boiling temperature. The resultingsteam is conducted through a fin-type condenser coil from which thedistillate emerges. In some designs a motor driven fan forces ambientair over the condenser fins for cooling and condensing the steam. Inother designs the condenser coil is water cooled by locating it in achamber into which the raw, comparatively cool water is fed before theraw water is conducted to the boiler, resulting in waste water. Mostdistillers on the market distill on a batch-by-batch basis rather thancontinually according to demand, as should be the case.

Among the reasons that installations of previously existing distillerdesigns have been small in number, although there is such a great needfor them, is that the distillers are configured in a way that makes themdifficult to install in a concealed and inconspicuous manner near thekitchen sink, where water is usually consumed in the home. Since anexisting type of distiller would ordinarily be installed near thekitchen sink, one possibility is to stand the prior art types ofdistillers on a counter top next to the sink. Yet, most householdersobject to dedicating to a distiller precious counter top area, which isusually felt to be insufficient in most residences in the first place.Installation inconvenience becomes a factor in deciding not to buy anydistiller presently on the market. Besides, most, if not all known priorart distillers can be characterized as lacking any redeeming aestheticcharacteristics.

Another place in which a prior art distiller might be installed is in acabinet near the kitchen sink. The problem with this is that prior artdistillers are vertically oriented, that is, they have one componentstacked on another so they have a tall profile or an inordinately greatheight dimension. As a practical matter, this means that they requirededication of a lot of below-the-counter top cabinet space, and itbecomes impossible to use any of the space in the cabinet, above, belowor on the sides of the distiller.

Besides deficiencies in aesthetic characteristics and excessive spaceutilization, prior art distillers are difficult to maintain in goodoperating condition, particularly, because of the difficulty of cleaningsediment and scale from the internal parts of the distiller. Most priordistillers require a substantial amount of disassembly and handling orworking on multiple parts to fully clean the boiler of scale. This maybe an aggravating factor that the user realizes only when the distillerfails to produce distilled water up to rated capacity. Facilitating easyand simple descaling and cleaning are problems that have frequently beenattacked but have not been completely solved in prior distiller designs.

SUMMARY OF THE INVENTION

One objective of the invention is to provide a distiller in which waterhandling components, the electric heating element, water and cooling airflow paths, the clean out tray and so forth can be horizontally orientedsuch that the distiller can and does have a low profile and an overallconfiguration that allows it to be installed in kitchen cabinetry withminimum sacrifice of space that can be used for other purposes.

Another objective of the invention is to provide a distiller that has awater heating chamber in which the electric heating element is onlypartially immersed in the infeed or raw water, so that only a small massor thin film of water is constantly being evaporated.

In a preferred embodiment, the partially immersed electric heatingelement is self-cleaning, without participation by the user.Self-cleaning or shedding of the scale from the heating element is doneby automatically raising the temperature of the heating element withoutcontact with water to cause the scale to break away and fall into thepreviously mentioned sediment collection tray of the new distiller.

The temperature control objective of the distiller is also met by afloat switch assembly that is the initiator of various controlfunctions. The float assembly senses the level of purified wateravailable for use and actuates the distillation process when the leveldrops to a predetermined low level. The float assembly also varies thepower delivered to the heating element according to the level ofpurified water. When the level corresponds to a lower than permissibledistilled water level, the heating element operates at a maximum powerlevel. When the purified water reaches an acceptable, but not yet fulllevel supply, the heating element operates at a reduced power level.

Another important objective resides in providing a distiller havingoperating portions that can be easily removed by the used for periodiccleaning or as otherwise required during distillation operations.

One aspect of this objective is met by providing a two part steamchamber. The lower part of the chamber is a tray that is separable fromthe upper steam chamber part. Consequently, the lower chamber tray canbe withdrawn from the distiller housing in the manner of a drawer foreasy removal and disposal of mineral and other solid residue that isprecipitated or concentrated from the raw water when water converts tosteam.

In this aspect of the invention, a gasket is present at the interface ofthe removable clean out tray and the steam chamber of the boiler.Closing a door from which the tray is withdrawn for cleaning causes somecamming surfaces on the tray to ride up on rollers that force the trayinto positive sealing relationship with the gasket on the remainingupper part of the steam chamber.

A preferred embodiment employs secondary latches that prevent accidentalwithdrawal of the sediment tray. The secondary latches (which preferablywould not be visible to a child) can be unlatched in a way that is notreadily apparent, to preclude accidental withdrawal of the tray when itcontains hot water.

Preferably, the two parts of the steam chamber extend lengthwisehorizontally by an amount that is much greater than the combined heightof the parts. In addition, an associated low profile condenser assemblydraws ambient air through a finned condenser coil. The air flow paths toand from the condenser also are all oriented horizontally. The result isa distiller having a low profile dimension that requires only a smallamount of cabinet space for installation, when compared to priordistillers.

The objective of easy cleaning is also met by providing a distillerhaving a purified water holding tank that can be readily swung into andout of a latched relationship with the remainder of the distiller formaintenance.

Another objective of the invention is to provide a steam chamber for awater distiller with features to actively prevent contamination. In oneembodiment, this objective is met by providing a baffle over the heatingelement in the steam chamber that serves several purposes. One purposeis to prevent small globules of hot water from entering the inlet of thecondenser, to thereby prevent possibly contaminated impure water frommixing with the distillate. The baffle also acts as a heat shield forthe top steam chamber, which can be plastic and would otherwise besubjected to a very high temperature, particularly when the heatingelement is allowed to rise to a temperature sufficiently high to causescale on the heating element to fracture and fall off into the sedimenttray.

The objective of preventing contamination is also met by providing acheck valve in the conduit through which steam flows from the steamchamber into the condenser. This check valve allows steam to pass whenthe steam chamber is operating while, on the other hand, prohibiting airto pass into the condenser and purified water holding water tank of thedistiller when the tray is removed for cleaning.

Another objective of the invention is to provide a distiller having acontrol system that automates distillation operations. Except forperiodic maintenance, the operations are independent of any userinvolvement. In one embodiment, the faucet through which purified wateris dispensed also includes a series of lights that convey systemoperation messages to the user.

How these and other more specific objectives and features of the newunitary low profile water distiller are achieved and implemented willnow be described in greater detail, with reference to the accompanyingdrawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cabinet in which a kitchen sink isinstalled and in which the new low profile water distiller is installed;

FIG. 2 is an enlarged perspective view of the water distiller shown inFIG. 1 installed in the cabinet and showing the air flow paths to andfrom the distiller;

FIG. 3 is an exploded perspective view of the major component parts ofthe water distiller shown in FIG. 2;

FIG. 4 is a perspective view of the top portion of the water distillershown in FIG. 2, with the top and side walls removed;

FIG. 5 is a view of the status and attend indicator lights mounted onthe faucet of the distiller shown in FIG. 1;

FIG. 6 is a top plan view of the water distiller shown in FIG. 4;

FIG. 7 is a profile elevation view of the right side of the waterdistiller shown in FIG. 4, taken generally along line 7--7 in FIG. 6;

FIG. 8 is an enlarged perspective view of the water level controller forthe holding tank associated with the distiller shown in FIG. 4;

FIGS. 9A, 9B, and 9C are a series of views of the float of the waterlevel controller shown in FIG. 8 at different positions depending uponthe level of water present in the holding tank;

FIG. 10 is a side section view of the boiler area of the water distillertaken generally along line 10--10 in FIG. 6;

FIG. 11 is a top perspective assembled view of the steam chamber area ofthe water distiller;

FIG. 12A is an exploded perspective view of the steam chamber area ofthe water distiller;

FIG. 12B is a bottom perspective assembled view of the steam chamberarea of the water distiller;

FIG. 13 is a bottom plan view of the steam chamber area of the waterdistiller;

FIG. 14 is a side elevation view of the steam chamber area of the waterdistiller showing the passage of water into the boiler area;

FIG. 15 is a side elevation view of the steam chamber area of the waterdistiller showing the passage of steam out of the area;

FIGS. 16A and 16B are a series of views of the water level controller inthe steam chamber area of the water distiller in use at different waterlevels in the heating chamber;

FIG. 17 is an exploded perspective view of the faucet associated withthe water distiller shown in FIG. 1;

FIG. 18 is a side sectional view of the faucet shown in FIG. 17;

FIG. 19 is a sectional side view of the drawer and removable trayassembly associated with the steam chamber area of the water distillershown in FIGS. 2 and 3, with the drawer shown in its closed and shutposition;

FIG. 20 is a sectional side view of the drawer and removable trayassembly associated with the steam chamber area of the water distillershown in FIGS. 2 and 3, with the drawer shown in an initially openedposition;

FIG. 21 is a sectional side view of the drawer and removable trayassembly associated with the steam chamber area of the water distillershown in FIGS. 2 and 3, with the drawer shown in its partially openedposition;

FIG. 22 is a perspective front view of drawer and removable trayassociated with the steam chamber area of the distiller shown in itspartially opened position;

FIGS. 23A and 23B are enlarged side section views, taken along line23--23 in FIG. 22, of the child-proof latching mechanism associated withthe drawer and removable tray associated with the steam chamber area ofthe distiller;

FIG. 24 is a side sectional view of the drawer and removable trayassembly associated with the boiler area of the water distiller, withthe drawer shown in its fully opened position;

FIG. 25 is a perspective exploded top view of the drawer and removabletray shown in FIGS. 19 to 24 removed from the distiller;

FIG. 26 is a bottom view of the bottom of the removable holding tankassociated with the water distiller shown in FIGS. 2 and 3;

FIG. 27 is a side section view of the removable holding tank shown inFIG. 26 when engaged with the rest of the water distiller during use;

FIG. 28 is a side section view of the removable holding tank shown inFIG. 26 when disengaged from the rest of the water distiller formaintenance;

FIG. 29 is an enlarged view of the exterior front panel associated withthe water distiller shown in FIG. 1, showing the ducts for circulatingair into the cabinet for use by the distiller;

FIG. 30 is a perspective view of the exterior front face panel that isshown in FIG. 29;

FIG. 31 is a perspective view of the exterior front face panel withoptional extension member;

FIG. 32 is a side section view of the panel shown in FIG. 30, showingits break away louvers;

FIG. 33 is a perspective view of a cabinet in which a kitchen sink isinstalled and in which the new low profile water distiller is installedin a different position than shown in FIG. 1;

FIG. 34 is an exploded view of the air duct system associated with thecabinet installation of the water distiller shown in FIG. 33;

FIG. 35 is a side sectional view of the air duct system shown in FIG.32; and

FIG. 36, composed of parts 36A and 33B, is a schematic diagram of theelectrical control circuitry including a microprocessor based controllerassociated with the water distiller than embodies the features of theinvention.

The invention is not limited to the details of the construction and thearrangements of parts set forth in the following description or shown inthe drawings. The invention can be practiced in other embodiments and invarious other ways. The terminology and phrases are used for descriptionand should not be regarded as limiting.

DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 shows a cabinet 10 as would be found in the kitchen of a typicalresidential dwelling. A typical two basin sink 11 is installed in thecounter top 12 of the cabinet. A usual general purpose, swinging faucet13 is mounted next to the sink 11 for providing possibly softened, butotherwise untreated hot and cold water. The cabinet includes swingingdoors 14 for accessing storage space within the cabinet 10.

FIGS. 1 and 2 show a new unitary low profile water distiller 15 thatembodies the features of the invention in one preferred manner ofinstallation within the cabinet 10.

As installed in FIGS. 1 and 2, the distiller 15 may be assumed to beoccupying a space that was occupied formerly by a cabinet drawer. Arelatively small portion of the distiller 15 is exposed to view througha front panel 16 located above one swinging cabinet door 14.

The distiller 15 operates on readily available alternating current fromthe building mains. As FIG. 1 shows, the distiller 15 has an electricalpower cord 17 that can be plugged into a convenience outlet 18 insidethe cabinet. Alternatively, the electric cord 17 can be hardwired toelectrical lines within the cabinet 10.

FIG. 1 shows a pipe 20 that connects to the cold water supply lines ofthe building for supplying water to the distiller 15. As will bedescribed in greater detail later, the distiller 15 purifies the waterby distillation. A pipe 23 connects the faucet 22 to the distiller 15(as FIGS. 1 and 2 show). The faucet 22 dispenses purified water from thedistiller 15. The faucet 22 also will be described in greater detaillater.

As FIG. 1 shows, despite the installation of the distiller 15 in thecabinet 10, a substantial amount of usable storage space still remainsbelow the distiller 15 behind the swinging cabinet doors 14. Only thedecorative front panel 16 of the distiller 15 is visible from the frontof the cabinet 10. As the arrows in FIG. 2 show, air is brought into andexhausted from the distiller 15 through openings in the front panel 16.This aspect of the distiller operation will be described in greaterdetail later.

Because of its compact, low profile design, the distiller 15 can beeasily installed in several different arrangements within a typicalkitchen cabinet. Instead of the cabinet drawer installation shown inFIGS. 1 and 2, the same distiller 15 can be installed in the base of thecabinet 10 (as FIG. 33 shows). In this installation, a shelf, not shown,can still be placed immediately over the top of the distiller, so thatmuch of the space in the cabinet 10 is still available for other uses.This installation employs a different arrangement for circulating air toand from the distiller 15 through the toe of the cabinet, as will bedescribed in greater detail later. Otherwise, the installation is almostidentical with the one shown in FIGS. 1 and 2.

Also because of its compact, low profile design, the distiller 15 can beeasily installed in other areas of a typical kitchen. For example, inanother alternate installation (not shown), the components of thedistiller can be rearranged and mounted within a conventionalrefrigerator for dispensing chilled purified water or preparing ice madefrom the purified water.

The compact, low profile design of the distiller 15 is caused by thepurposeful arrangement of interior component parts that convert thesupply water to steam, condense the steam into purified water, anddispense the purified water. FIGS. 3 and 4 show the major interiorcomponent parts and their general arrangement within the distiller 15.

The distiller 15 includes a base 24 and an attached cover member 25 thattogether enclose an interior area that houses the major interiorcomponent parts. The decorative front panel 16 attaches to the covermember 25 to further enclose the interior area. The interior area housesa steam chamber assembly 26, a condenser assembly 27, a purified waterdispensing assembly 28, and an operation control module 29. A holdingtank 30 removably connects to the base 24 and forms a part of thepurified water dispensing assembly 28.

I. THE STEAM CHAMBER ASSEMBLY

The details of the steam chamber assembly 26 will be first described Thesteam chamber assembly 26 receives water from line 20 and converts thewater into steam. The steam chamber assembly 26 includes a water heatingchamber 31. An upright shroud 32 attached to the base forms the sidewallof the water heating chamber 31. A steam chamber cover 33 forms the topof the water heating chamber 31. The steam chamber cover 33 carries anelectrical water heating element 34.

A drawer 35 forms the bottom of the water heating chamber 31. The drawer35 carries a tray 36 in which water is boiled and converted to steam byoperation of the water heating element 34. The steam chamber cover 33receives the steam and conveys it to the condenser assembly 27 in a waythat will be described in greater detail later.

FIGS. 6, 7, and 10 to 16 shown further details of the construction ofthe steam chamber assembly 26. Raw (that is, undistilled) water issupplied through the pipe 20 that connects to the inlet of a valve 37.The valve 37 is actuated electrically by a solenoid 21. An inlet conduit38 connects to the outlet of the valve 37 for delivering water to thewater heating chamber 31 via an inlet port 39 formed in the steamchamber cover 33 (best shown in FIG. 14). The solenoid 21 operates thevalve 37 to supply water to the heating chamber 31 based upon commandsignals provided by the microcontroller module 29, as will be describedin greater detail later.

FIGS. 10 to 12 show further details of the structure of the steamchamber cover 33. The steam chamber cover 33 includes an outer shell 40that is fastened to the shroud 32. The outer shell 40 forms an inverteddome that defines the inside volume of a steam receiving chamber 41positioned above the water heating chamber 31 (See FIG. 10). The outershell 40 is preferably made of a plastic or noncorrosive metal materialwith a relatively high tolerance for heat.

A. CONTROL OF STEAM DISPERSAL WITHIN THE STEAM CHAMBER

A baffle 42 extends between the water heating chamber 31 and the steamreceiving chamber 41. The baffle 42 is also preferably made of anoncorrosive metal with a relatively high heat tolerance. The baffle 42is suitably fastened (using noncorrosive bolts or screws) to inwardlyextending posts 43 of the outer shell 40. As FIG. 10 best shows, theposts 43 extend at unequal lengths so that, when fastened, the topinterior surface 44 of the baffle 42 extends at an angle relative to thewater heating chamber 31. As FIG. 10 also best shows, the side walls 45of the baffle 42 also extend at unequal lengths from the top bafflesurface 44 so that they compensate for the slope of the surface 44 andterminate along generally the same horizontal plane. The baffle sidewalls 45 include horizontally elongated slots 46 near their junctionwith the top baffle surface (as FIGS. 12A and 12B best show). The baffleside walls 45 also extend into the water to temper the temperature ofthe baffle 42 during distillation operations described later.

When heating element 34 energizes, there is vigorous boiling andagitation of the water at its surface 47 within the water heatingchamber 31 (see FIG. 10). This results in small globules of water beingpropelled upward toward the steam receiving chamber 41 along with thesteam. The steam escapes through the slots 46 into the steam receivingchamber 41. However, the larger water globules impact the top interiorbaffle surface 44, which blocks their passage into the steam receivingchamber 41. The water globules follow the slope of the baffle surface 44and fall back into the water heating chamber 31.

Therefore, the baffle 42 allows only formed steam to enter the steamreceiving chamber 41. The baffle 42 continuously returns water globulesformed in the boiling process back into the heating chamber 31 forconversion into steam.

B. TEMPERATURE CONTROL WITHIN THE STEAM CHAMBER

As FIGS. 10 to 12 best show, the steam chamber cover 33 includes aninwardly extending heat sink 48 to which the electric heating element 34is fastened by a mating clamp 49. When fastened, the clamp 49 forms aheat conducting part of the overall heat sink body. The clamp 49includes a bottom surface 49a.

As FIGS. 10 and 12A show, the heating element 34 has a short section 50that is deflected out of the plane of the remainder of the horizontallyoriented heating element 34. The clamp 49 connects this deflectedportion 50 of the heating element 34 to the heat sink 48 (as FIGS. 16Aand 16B also show).

The heat sink 48 contains a top cavity 51 (see FIGS. 16A and 16B). Thecavity 51 holds a heat sensor element 52. The sensor element 52 is inheat exchange relationship with the overall heat sink body 48 and 49.Two electric leads 53 extend out of the heat sensor element 52 and areoperatively connected to the operation control module 29.

The heat sensor element 52 carried within the heat sink 48 is preferablya commercially available solid state device whose resistance varieslinearly in relation to the temperature to which it is exposed. Thespecific operation of the sensor 52 and its relationship with thecontrol module 29 will be described in greater detail later.

The offset between the two heating element portions 34 and 50 creates avertical space or gap (identified by the letter G in FIGS. 16A and 16B)between the bottom clamp surface 49a and the bottom surface of the mainsection of the heating element 34. As the following Examplesdemonstrate, the vertical height of the gap G directly influences thelevel at which water is maintained in the water heating chamber 31relative to the heating element 34 during the distillation process.

As the water level 47 in the water heating chamber 31 falls due toevaporation during the distillation process, progressively more of theheat sink 49 is exposed. When the meniscus of the water breaks from thebottom clamp surface 49a (as shown in FIG. 16B), the temperature sensedby the element 52 will increase rapidly. However, because the heat sink49 is offset above the element 34, the water is still in contact theelement 34, even though it is not in contact with the heat sink 49.Thus, as the temperature of the heat sink 49 rises, the temperature ofthe element 34 itself will remain relatively constant at itsdistillation temperature (about 100 degrees C). Film boiling at theelement 34 continues.

The rapidly rising temperature sensed by the element 52 will quicklyreach a predetermined high end control temperature (about 110 degreesC). The operation control module 29 responds to this condition byenergizing the solenoid coil 21 to open the inlet valve 37. This opensthe flow of undistilled source water into the water heating chamber 31(through the previously described conduit 38 and port 39).

As the water level rises within the heating chamber 31, it will againmake contact with the heat sink 49 (as FIG. 16A shows). The heat sinkbody 48 and 49 will experience a rapid temperature drop. The sensor 52detects when the temperature drops below the high end controltemperature, or another preselected control temperature less than thehigh end control temperature. The operation control module 29 respondsto this condition by de-energizing solenoid coil 21 to close the inletvalve 37. This stops the flow of undistilled source water to the waterheating chamber 31 (through previously described conduit 38 and port39).

The control cycle continuously replenishes evaporated water with sourcewater under the control of the offset sensor element 52 enclosed withinthe heat sink body 48 and 49.

The vertical height of the gap G directly controls the variance in thewater level 47 in the heating chamber 31. Because of the rapid rise intemperature of the heat sink body 48 and 49 at the time the meniscusbreaks from the bottom clamp surface 49A, the water level at whichreplenishment source water is brought into the heating chamber 31 can beclosely controlled. The element 34 is kept in constant contact withwater, and film boiling continues. The generation of significant radiantheat, which would occur if the water were allowed to drop below theelement 34, is avoided. The generation of radiant heat is undesirable,as it fatigues the surrounding materials.

Because of the rapid fall in temperature as replenishment water againmakes contact with the clamp 49, the water level at which the supply ofreplenishment source water is terminated is also closely controlled.

In the preferred and illustrated embodiment, the size of the gap G isselected so that the water level is maintained during the distillationprocess within 1/8 inch above and below the centerline of the heatingelement 34. At this level, optimal conditions for film boiling exist.

In the illustrated embodiment, the element 34 has a diameter of about5/16 inch. The offset between the centerlines of the element 34 and theoffset portion is about 3/16 inch. The bottom clamp surface 49 hangsabout 1/16 inch below the bottom surface of the offset portion 50,creating a gap G of about 1/8 inch. When undergoing evaporation, themeniscus of the undistilled water is also observed to rise about 1/8inch above the median surface of the water.

The material from which the heat sink body 48 and clamp 49 are made willalso influence the level of water maintained. In the illustrated andpreferred embodiment, the bodies 48 and 49 are made of a highnoncorrosive heat conductive material like copper.

The flow rate at which undistilled source water is brought into theheating chamber 51 will also influence the replenishment time. In apreferred arrangement (to be described in greater detail later), theelement 34 can be turned off when the high end control temperature isreached (simultaneously with the opening of the inlet valve 37) toquicken the time it takes to cool down the heat sink 49. In thisarrangement, the element is turned back on when the temperature dropsbelow the high end control temperature, or another preselected lowertemperature.

The following Example demonstrates the benefits of this aspect of theinvention.

EXAMPLE

Test #1

A copper heat sink like that shown in FIGS. 16A and 16B was clamped toan electrical heating element. However, unlike the heating element shownin FIGS. 16A and 16B, the heating element in Test #1 was generallycoplanar in overall configuration (that is, it did not include theoffset portion 50). The bottom surface of the heat sink (correspondingto the bottom surface of the clamp 49) extended about 1/16-inch belowthe bottom surface of the heat element. A heat sensor element 52comprising a Micro Switch TD5A RTD was carried within the heat sink.

The heating element and heat sink assembly were submerged in water in asteam chamber, and power was applied to the element to boil the water.

As the water evaporated, the water level fell to a point where themeniscus of the water broke away from the bottom surface of the element(the meniscus was observed to rise about 1/8 inch above the normal planeof the water). However, the lower extending bottom surface of the heatsink continued to be submerged in the water, still cooling the heatsensing element. As a result, the surface temperature of the elementsoared to about 600 degrees C before the heat sink reached its high endcontrol temperature set at about 110 degrees C.

This arrangement was unsatisfactory because (i) a significant amount ofradiant heat was generated in the steam chamber, (ii) there was no filmboiling occurring after the meniscus of the water broke away from theheating element and before the heat sensor reached its high end controltemperature to admit more water into the steam chamber, and (iii) thewater level within the steam chamber fluctuated significantly above andbelow the centerline of the heating element (where most effective filmboiling conditions exist).

Test #2

In this test, a heating element with an offset portion 50 was used. Thecenterline of the offset portion 50 was spaced about 1/4 inch above thecenterline of the rest of the element. A copper heat sink like thatshown in FIGS. 16A and 16B was clamped to the offset portion. The lowersurface of the heat sink (i.e., the bottom of the clamp 49) extendedabout 1/16 inch below the bottom surface of the offset portion, creatinga gap of about 3/16 inch between the lower surface of the heat sink andthe lower surface of the main section of the element. A heat sensorelement 52 comprising a Micro Switch TD5A RTD was carried within theheat sink.

As in Test #1, the heating element and heat sink assembly were submergedin water in a steam chamber, and power was applied to the element toboil the water.

In this arrangement, the meniscus of the boiling water broke away fromthe bottom surface of the heat sink while the main portion of theheating element was still submerged in the water. When the heat sensorreached its high end control temperature of 110 degrees C. (therebyadmitting more water into the steam chamber), the main portion of theheating element was still at its desired film boiling temperature ofabout 100 degrees C.

The generation of significant radiant heat (observed in Test #1) waseliminated in Test #2. However, it was observed that the water levelwithin the steam chamber still fluctuated somewhat above and below thedesired level at the centerline of the heating element, although therange of the variance was significantly reduced, when compared to thevariance observed in Test #1.

Test #3

As in Test #2, a heating element with an offset portion 50 was used.However, the offset (again, as measured between the centerlines of theoffset portion and the main element portion) was reduced to about 3/16inch. A copper heat sink like that shown in FIGS. 16A and 16B wasclamped to the offset portion. The lower surface of the heat sink (i.e.,the bottom of the clamp 49) still extended about 1/16 inch below thelower surface of the offset portion, creating a gap of about 1/8 inchbetween the lower surface of the main element and the lower surface ofthe main section of the element (which approximates the normal rise ofthe water meniscus observed in the tests). A heat sensor element 52comprising a Micro Switch TD5A RTD was carried within the heat sink.

As in the other tests, the heating element and heat sink assembly weresubmerged in water in a steam chamber, and power was applied to theelement to boil the water.

In this arrangement, the meniscus of the boiling water broke from thebottom surface of the heat sink while the main portion of the heatingelement was still submerged in the water. When the heat sensor reachedits high end control temperature of 110 degrees C. (thereby admittingmore water into the steam chamber), the main portion of the heatingelement was still at its desired film boiling temperature of 100 degreesC.

As in Test #2, the generation of significant radiant heat (observed inTest #1) was eliminated. Furthermore, the water level within the steamchamber was maintained generally within 1/8 inch above and below thecenterline of the heating element.

Tests #1, #2, and #3 demonstrate the benefits of locating the heatsensing element within a heat sink body above the surface of the mainheating element. The use of the offset prevents the generation of highradiant heat in the steam chamber during the distillation cycle bycontinuously maintaining contact between the water and the main portionof the heating element. Test #1, #2, and #3 also demonstrate that theamount of offset controls the variance in the water level with respectto the heating element during the distillation process. The use of theoffset permits the control of the water level within the steam chamberat the optimal range for film boiling.

The sensor element 52 anticipates rises and falls in temperature alongthe main body of the heating element 34 by sensing temperature at thedeflected short portion 50 of the element 34 that is positioned abovethe main body of the element 34 and the water level present within thechamber 31. The distiller 15 can thereby maintain a consistent waterlevel over the main body of the element 34 that is ideal for generatingsteam. The distiller 15 does not over-submerge the heating element, butinstead maintains a thin film of water along the centerline of theheating element 34, where it can be continuously converted to steam.

C. CLEANING THE STEAM CHAMBER

The control module 29 of the distiller 15 preferably periodicallyoperates in a self-cleaning mode that overrides the normal operation ofthe sensor element 52 as just described. In the self-cleaning mode, thecontrol module 29 allows the water level 47 to drop below the levelshown in FIG. 16B by closing the inlet valve 37. During theself-cleaning mode, the heating element 34 operates for a sufficientperiod to create temperatures above that needed for distillation (forexample, temperatures exceeding 150° C.) The high temperature causesaccumulated scale to fracture from the element 34 and drop into the tray36. The self-cleaning mode ends after a predetermined temperature isachieved.

The drawer 35 can be operated periodically open the steam chamberassembly 26 to remove the tray 36 for cleaning and disposal of the scaledeposited during the self-cleaning mode just described.

FIGS. 10 and 19 to 25 best show the details of the drawer 35 andremovable tray 36. The drawer 35 removably receives the tray 36 (as FIG.25 shows). The drawer 35 (carrying the tray 36) is movable between fullyclosed position (see FIGS. 10 and 19) and a fully opened position (seeFIGS. 21 and 22).

The distiller 15 includes a latching mechanism 54 carried on thedecorative front panel 16 for manipulation by the user. By operating thelatching mechanism 54, the user can move the drawer 35 between its fullyopened and fully closed position.

The latching mechanism 54 includes a swinging drawer front 55 thatincludes a pair of side wings 56. The side wings 56 are each pivotallymounted by a pin 57 to the panel 16. The drawer front 55 thereforeswings about the pins 57 between a fully closed position (as FIG. 19shows) and a fully opened position (as FIG. 24 shows). Each side wing 56includes a camming groove 58 that receives a pin 59 carried on eachfront edge of the drawer 35 (see FIG. 3 also).

The drawer 35 further includes a curved rearward camming surface 60 thatrides along a camming roller shaft 61 as the drawer 35 moves between itsfully open and closed positions. The camming shaft 61 is mounted forrotation on two laterally spaced apart supports 70 on the shroud 32 (seeFIG. 3). Two rubber o-rings 71 on the shaft 61 resiliently bear againstthe camming surface 60.

The user can move the drawer 35 within the distiller 15 by opening andclosing the swinging drawer front 55 on the panel 16.

More particularly, as the drawer front 55 moves toward its closedposition, the drawer 35 (carrying the tray 36) also moves toward itsfully closed position. The camming action of curved surface 60 along theroller shaft 61 (and o-rings 71) raises the drawer 35 away from the base24 of the distiller 15. This in turn presses the top surface of thedrawer 35 against a gasket 62 (see FIG. 19). Upon arriving at its fullyclosed position, the drawer 35 lodges in full sealing relationship withthe outer shell 40 of the steam chamber cover 33.

As the drawer front 55 moves toward its opened position, the drawer 35(with tray 36) also moves toward its fully opened position. The cammingaction of curved surface 60 along the roller shaft 61 (and o-rings 71)gently lowers the drawer 35 toward the base 24 of the distiller 15. Thisin turn breaks the sealing relationship between the drawer 35 and theouter shell 40 of the steam chamber cover 33. Upon reaching its fullyopened position, the drawer 35 can be removed by sliding out of theassociation with the steam chamber assembly 26 of the distiller 15.

In the illustrated and preferred embodiment, the latching mechanism 54includes a lock assembly 63 that maintains the swinging drawer front 55in its fully closed position. As FIGS. 19 and 20 best show, the lockassembly 63 includes a locking button 64 that extends from the frontpanel 16. The locking button 64 is movable between a normal position(shown in FIG. 19) and a depressed position (shown in FIG. 20). A spring(not shown) biases the button 64 toward its normal position.

The lock assembly 63 also includes a locking pin 65, a transverseportion of which rides upon a cam surface 66 formed on the interior endof the button 64. When the button 64 is in its normal position, thelocking pin 65 extends downward through a latch opening 67 in the top ofthe swing drawer front 55. The interference of the pin 65 within theopening 67 locks the drawer front 55 in its fully closed position. Whenthe button 64 is depressed (as FIG. 20 shows), the pin 65 rises alongthe cam surface 66 out of the opening 67, allowing the user to open thedrawer front 55.

In the illustrated and preferred embodiment (see FIGS. 21 to 23), thelatching mechanism 54 also includes a "child-proof" latching featuresthat prevents the drawer front 55, once unlocked and opened, from beingimmediately brought to a fully open position.

More particularly, the latching mechanism 54 includes a pair ofoutwardly extending tabs 68 formed on each side wing 56. The tabs 68abut against adjacent side edges 69 of the panel 16 when the drawerfront 55 reaches an intermediate position between its fully opened andfully closed position (shown in FIGS. 21 and 22). The tabs 68 therebyprevent further opening of the drawer front 55. This arrangementprohibits anyone, particularly a child, from withdrawing the drawer 35without regard to the fact that it may have hot water in it.

The side wings 56 are resiliently movable by an adult user in the areasurrounding the tabs 68. By moving the side wings 56 toward each other,the adult user can free the tabs 68 from the side edges 69 (see FIG.23B), thereby allowing the drawer front 55 to be brought into its fullyopened position.

As will be described later, the control module 29 notifies the user whenit is time to open the drawer 35 and remove the tray 36 for cleaning.

The removable tray 36 (see FIG. 25) preferably is made of a temperatureresistant plastic material. In this way, the plastic tray 36 may bedisposed of and replaced with a clean tray 36 after each self cleaningmode.

Alternatively, the tray 36 can be made of a more durable material forrepeated use. In this embodiment, the tray 36 can be scrubbed to removethe sediment or can be placed in an automatic dishwasher for cleaning.

Because all sediment including minerals and other solids derived fromthe raw water can only accumulate in the tray 36, nothing more needs tobe done by the user to clean the distiller.

D. CONTAMINANT CONTROL IN THE STEAM CHAMBER AND BEYOND

In the illustrated and preferred embodiment (as FIG. 25 shows), the tray36 includes an interior cavity 72 for holding a water solubledisinfecting material. In the illustrated embodiment, the disinfectingmaterial is in the form of a pill 73 placed into the cavity 72. Aremovable patch 74 overlies the pill-containing cavity 72. The patch 74can be removed by the user at the time the tray 36 is placed into thedrawer 35 for use. Alternatively, the patch 74 can be made of an inertmaterial that dissolves when contacted by water.

Water in the water heating chamber will dissolve the disinfectingmaterial. The disinfecting material will eventually be carried by thedistillation process to the other parts of the distiller 15, therebydisinfecting them.

The steam chamber assembly 26 includes a conduit 75 that conducts steamfrom the steam receiving chamber 41 to the condenser assembly 27. Theconduit 75 forms an integral part of the outer shell 40 and connects totubing 76 that extends along a horizontal plane to the condenserassembly 27.

The steam chamber assembly 26 includes a check valve 78 for openingcommunication between the steam receiving chamber 41 and the condenserassembly 27 only when steam is present. Without steam pressure, thecheck valve 78 blocks communication between the steam receiving chamber41 and the condenser assembly 27.

FIG. 15 shows the details of the check valve 78. The conduit 75 forms acheck valve chamber 79. When normal atmospheric pressure conditionsexist within the chamber 79, the check valve 78 rests upon an annularbeveled seat 80 to close the conduit 75.

When steam is being generated, steam pressure in the chamber 41 rises toslightly above atmospheric pressure. The increased steam pressure liftsthe check valve 78 to the position shown in phantom lines in FIG. 15.The up-lifted check valve 78 opens the conduit 75 to allow steam to passto the condenser tube 38. As steam continues to flow, the check valve 78is urged further toward its up-lifted position by the negative pressurethat develops in the condenser assembly 27 because of the steam or hotvapor condensing to a liquid, which reduces its volume.

One important reason for employing the check valve 78 is to preventambient air from freely flowing into the condenser assembly 78. Thiscan, in turn, result in the ambient air carrying contaminants into theholding tank 30. The potential for this occurring is the greatest whenthe drawer front 55 opens and the drawer 35 is withdrawn. The ambientair can be contaminated with molecules that are sensed as odoriferous orthat impart an unpleasant taste to the distilled drinking water. Therealso may be microorganisms in the air that might thrive in the distilledwater. The check valve 78 is effective to block access by contaminantsto the interior regions of the distiller.

II. THE CONDENSER ASSEMBLY

FIGS. 3, 4, and 6 best show the details of the condenser assembly 27.

The condenser assembly 27 includes a finned condenser coil 81. As beforedescribed, the steam from the steam receiving chamber 41 is dischargedthrough conduits 75 and 76 to the inlet 82 of the condenser coil 81. Thecondenser coil 81 includes several generally vertically oriented coolingfins 83. The steam follows a serpentine path 84 past the cooling fins83, where it condenses into distilled water. The condensed, distilledwater exits the path 84 through an outlet 84a into the holding tank 30(as best shown in FIGS. 4 and 7).

During the condensation process, the distiller 15 continuouslycirculates air through the fins 83 to cool them. Arrows in FIGS. 2, 3,4, and 6 show the air flow path through the distiller 15. A fan 85 drawsair in through an intake opening 86 in the back of the cover 25.Preferably, an air filter 141 occupies this opening 86.

Ambient air is brought to the intake opening 86 of the distiller 15through a series of inlet vents 87 formed in a face panel 160 that fitsover the front panel 16 (see FIG. 2). The fan 85 directs the air throughthe fins 83 and then past the shroud 32. The air exits an out take vent88 in the front panel 16. The FIGURES show a single out take vent 88,although more than one can be provided. As FIGS. 2 and 4 best show, airflows in an essentially horizontal plane through the fins 83 and throughthe interior of the distiller 15.

FIGS. 29 to 32 show the details of the construction of the frontdecorative face panel 160 that includes the inlet air vents 87. Thefront panel 16 of the distiller 15 fits through an opening 165 formed inthe face panel 160. As FIG. 30 shows, the face panel 160 has ahorizontal width that matches the drawer size of most residentialcabinets. Still, as FIG. 31 shows, the width of the panel 160 can beenlarged by an optional panel extender 161 attached by a bracket 162.

The vertical height of the panel 160 is adjustable on site by a seriesof frangible louver sections 163. A line of weakness 164 is formed onthe back of the panel 160 between each louver section 163. As FIG. 32shows, one or more louver sections 163 can be conveniently broken awayby the user to create the vertical height required for the installation.When viewed from the front, the frangible louver sections 163 form adecorative pattern.

FIGS. 33 to 35 show an alternate arrangement for circulating air to andfrom the distiller 15 when installed in the base of the cabinet 10. Inthis arrangement, ambient air is brought to the distiller 15 through aninlet duct 150 cut in the toe of the cabinet 10. The air flow within thedistiller 15 shown in FIG. 33 is the same as shown in FIGS. 4 and 6.

The air exiting the distiller through outlet vent 88 is channeled by wayof an exterior baffle 151 through an outlet duct 152 cut in the toe ofthe cabinet 10. The baffle 151 fits through a plate 153 on the distillerbase 24 that can be removed to adapt the distiller for the installationshown in FIGS. 33 to 35.

III. THE PURIFIED WATER DISPENSING ASSEMBLY

The purified water dispensing assembly 28 includes the tank 30 thatreceives the distilled, purified water for dispensing through the faucet22. The holding tank 30 is preferably made of a plastic that isacceptable for contacting materials to be ingested by humans. Theholding tank 30 includes an air vent 93 that includes an inline bacteriafilter. In a preferred embodiment, the holding tank 30 contains abouttwo gallons of distilled water.

A. WATER LEVEL CONTROL IN THE HOLDING TANK

As FIGS. 3, 4, and 7 best show, the purified water dispensing assembly28 includes a distilled water delivery pump 89 that is controlled by thecontrol module 29 through the operation of a float switch assembly 90.FIGS. 8 and 9 shown further details of the float switch assembly 90.

The float switch assembly 90 includes a siphon tube 91 that extends apredetermined distance into the holding tank 30. The inlet side of thepump 89 connects by the tubing 92 to the siphon tube 91 to draw waterthrough the siphon tube 91 out of the tank 30. The outlet side of thepump 89 connects to the conduit 23 that leads to the faucet 22.

The float switch assembly 90 also includes a sample tube 94 next to thesiphon tube 91. A water quality probe 95 occupies the sample tube 94.The probe 95 continuously measures the conductivity of the purifiedwater and thereby senses the amount of total dissolved solids present.The sensor 95 conveys this information to the control module 29 for usein a way that will be described in greater detail later.

As FIGS. 9A, 9B, and 9C show, the sample tube 94 also contains a seriesof three reed switches, designated 96, 97, and 98. A member 99 encirclesthe sample and siphon tubes 91 and 94. The member 99 floats upon thewater within the tank 30 and therefore rises and falls according to thewater level present in the tank 30. The float member 99 carries a magnet100. The magnet 100 actuates the reed switch 98 when the float member 99is in the low water level position shown in FIG. 9A. The magnet 100actuates the reed switch 97 when the float member 99 is in theintermediate water level position shown in FIG. 9B. The magnet 100actuates the reed switch 96 when the float member 99 is in the highwater level position shown in FIG. 9C. The reed switches 96, 97, and 98convey information to the control module 29. The control module 29 usesthis information to control distillation in a way that will be describedin greater detail later.

However, generally speaking, the control module 29 will fully activatethe steam chamber assembly 26 to generate distilled water at a maximumrate when the float member 99 reaches the low water level position (FIG.9A). The control module 99 reduces the rate at which distilled water ismade when the float member 99 reaches the intermediate water levelposition (FIG. 9B). The control module 29 will stop operation of thesteam chamber assembly 26 when the float member 99 reaches the highwater level position (FIG. 9C).

B. REMOVABLE HOLDING TANK

FIGS. 26, 27, and 28 show that the holding tank 30 can be easilydetached from the base 24 of the distiller 15 for maintenance andcleaning.

More particularly, the rear of base 24 includes a pair of hook members101. The rear of the holding tank 30 includes a pair of outwardlyextending tabs 102 that mate with the hook members 101. When mated, theholding tank 30 can be pivoted into a generally horizontal positionagainst the underside of the base 24 (as FIGS. 26 and 27 show). A latch103 on the front of the tank 30 releasably engages a downwardlydepending hook 104 on the underbody of the base 24 to secure the tank 30in position against the base 24. A gasket 110 seals the interfacebetween the tank 30 and the underside of the base 24.

As FIG. 28 shows, by releasing the latch 103, the holding tank 30 can beswing away from the base 24 to release the mating hooks 101 and tabs 102to thereby free the tank 30 from the base 24.

C. PURIFIED WATER DISPENSING FAUCET

FIGS. 17 and 18 best show the details of the purified water faucet 22.

The faucet 22 serves several purposes besides being operable to drawdrinking water. It contains a final filter 105 for the distilled water.The final filter 105 adsorbs any gases that may be dissolved in thedistilled water. The final filter 105 also removes any vestiges of thedisinfecting material 73 added to the water.

The faucet 22 also receives signals from the control module 29 forcommunication to the user. For this purpose, the faucet 22 includes asmall display panel 106 (also shown in FIG. 5). The display panelincludes several light emitting diodes (LED's) which in the illustratedembodiment number three, 107, 108 and 109. A multiple conductor cable123 connect the diodes 107, 108, and 109 with the control module 29. Thediodes 107, 108, and 109 flash on and off under the control of thecontrol module 29 to indicate certain operational conditions prevailingin the distiller 15. The diodes 107, 108, and 109 also signal the userto take certain maintenance action, such as removing the drawer 35 fordisposal of mineral or sediment, or changing the faucet filter 105. Theoperation of the diodes 107, 108, and 109 will be described in greaterdetail later.

The faucet 22 includes a base 111 in which a valve member 112 isrotatable by a handle 113. The valve member 112 has a through-hole 114.By rotating the handle 113, the hole 114 is aligned with the bore of theinfeed pipe 23 to permit distilled water to enter a spout 115 throughthe filter 105.

FIGS. 17 and 18 show that the handle 113 and valve member 112 can bearranged to accommodate either left hand or right hand operation.

The filter 105 contains carbon particles 116. An open cell foam disk 117passes water to the spout 115, but prohibits the carbon particles 116from being carried along in the water stream.

The faucet 22 mounts in a suitable opening on the counter top 12 (seeFIGS. 1 and 2) and locks in place with a nut 118.

A decorative housing 119 encloses the filter 105. The spout 115 isattached by a nut 122 to the housing 119 for pivotal side-to-sidemovement. The housing 119 can be screwed on to and off the faucet base111 to permit easy removal and replacement of the filter 105. The filter105 includes top and bottom o-rings 120 that are seated with respect tothe valve member 112 and the spout 115 when the housing 119 is screwedinto place to capture the filter 105 within the housing 119.

The filter 105 can be easily replaced after it has been used andadsorbed enough water entrained organic or volatile organic contaminantsto saturate the carbon filter material. No tool is necessary for thisoperation. Also, since the filter 105 is located between the valvemember 112 and the spout 115, the filter 105 can be removed withoutdeactivating the inlet pump 89 or otherwise depressurizing the purifiedwater inlet line 23.

A check valve 124 (see FIGS. 4 and 5) maintains pressure in the conduit23 between the pump 89 and the valve member 112 of the faucet 22.

IV. LOW PROFILE CONFIGURATION

As FIGS. 4 and 6 best show, the compact, low profile design of thedistiller 15 is caused by the essentially horizontal arrangement ofinterior component parts that convert the supply water to steam,condense the steam into purified water, and dispense the purified water.The compact, low profile design is also caused by the essentiallyhorizontal flow of water and air through the distiller during use.

As FIGS. 4 and 6 show, the steam chamber assembly 26 has a horizontaldimension greater than its vertical height. The condenser assembly 27also has a horizontal dimension greater than its vertical height. Theoverall vertical height of the condenser assembly 27 is generally thesame as the overall vertical height of the steam chamber assembly 26.

The raw (undistilled) water is delivered to the steam chamber assembly27 in a path arranged along a generally horizontal plane. Steam is alsoconveyed from the steam chamber assembly 26 to the condenser assembly 28in a path arranged along a generally horizontal plane that is parallelto the generally horizontal plane of the raw water supply.

Cooling air is also drawn through the condenser assembly 27 in agenerally horizontal path that is parallel to the generally horizontalplanes of the raw water and steam delivery paths.

V. THE OPERATION CONTROL MODULE

FIG. 36 shows the details of the operation control module 29, which willnow be described in conjunction with the rest of the drawings.

The module 29 includes a DC power supply 300. Referring to the lowerleft hand corner of FIG. 36, lines L1 and L2 are the input for the powermain voltage. This is usually 120 volts AC in the residential dwellingswhere the distiller 15 is installed. A fuse in the input line serves theusual circuit overload protecting function.

The primary winding of a step down transformer 130 (see also FIG. 3) isconnected across lines L1 and L2. The output leads of the secondarywinding are the input to the DC power supply 300. The power supply 300is conventional in that it contains a rectifier bridge and an integratedcircuit voltage regulator, neither of which are shown but which are wellknown to electronic circuit designers. Low voltage DC is supplied to thecontrol module 29 by way of line 301, which is connected to the outputterminal of the DC power supply 300. Another line 302 leads to ground303.

The output Voltage of the DC power supply 300 depends on the operatingvoltages of the various circuit components of the control module 29. Inthe illustrated embodiment, the output voltage is 5 volts DC.

The heart of the control circuitry is a microcontroller that is solabeled and identified further by the reference numeral 304. Themicrocontroller 304 is carried on a circuit board that is attached tothe base 24 of the distiller 15 in the air flow path (as FIGS. 3 and 4best show).

Suitable microcontrollers are available from several sources. Themicrocontroller 304 selected for use in the product is a Motorolla MC 68HC 05 P8P type. It has on board read/write memory, read only memory andanalog-to-digital (A/D) converters. Of course, it also contains theusual components of a microcomputer. The application program is storedin the on-board read-only (ROM) on the microcontroller chip.

A positive 5 volts DC is applied to the microcontroller 304 by way ofline 305. Timing of certain system functions is governed by a clockpulse generator that is represented by the rectangle marked 306 andlabeled "clock." The clock signals are delivered to the microcontroller304 by way of a line 307. One terminal of the clock 306 connects to aground line 308.

The right region of FIG. 36 shows the electrical components that aresupplied with 120 volts AC. These components include the water heatingelement 34; the solenoid coil 21 for operating the water infeed valve37; the motor for the cooling fan 85; and the pump 89 that suppliespurified water to the faucet 22. These components are fed with 120 voltsAC by way of a common line L1.

The heating element 34, solenoid 21, fan motor 85, and pump 89 becomeenergized when their output lines 310, 311, 312 and 313 become connectedto L2 by individual switching circuits. The switching circuits arerepresented generally by the reference numerals 314, 315, 316 and 317.Switching circuits 314-317 are similar so only circuitry 314 will bedescribed.

The switching circuit 314 contains a triac 318 that connects the outputline 310 of the heating element 34 to AC line L2. The triac 318 becomesconductive when its control electrode 319 is supplied with a triggerpulse from a triac driver 320. The driver 320 transmits trigger signalsto the triac control electrode 319 in response to its associated line321 going low at power line frequency or, in other words, when broughtdown to a low logical level compared with the 5 volt DC power supplyvoltage. Switching circuit 314 and the other switching circuits 315,316, and 317 have DC voltage applied to them by way of having a commonline marked 322.

Line 321 is brought down to a low logic level as the result of theaction of an integrated circuit represented by the rectangle marked 323and labeled "interface drivers." The signal to connect line 321 toground is, of course, initiated by a corresponding signal delivered byway of line 324 from the microcontroller 304 to an input pin of theinterface driver circuit.

As is well known to electronic circuit designers, an interface driver isoften used to overcome the problem of microcontrollers that can sinkvery low level currents. Thus, the drivers respond to a signal from themicrocontroller 304 to ground the line by making the ground connectionin isolation from the microcontroller. There are capacitors andresistors, as shown, associated with the triac to filter radio frequencyinterference voltages that are incidental to triac operation.

It will be evident from inspection of FIG. 36 that the other switchingcircuits have lines corresponding to line 321 connected to output pinsof the interface drivers integrated circuit 323. Similarly, the triacsin these switching circuits are made conductive by signals initiated bythe microcontroller 304.

It should be understood that relays, not shown, could be used instead oftriacs to connect and disconnect the heating element 34, the infeedvalve control solenoid 21, the fan motor 85 and the pump motor 89 toline L1.

A. THE DISTILLATION CYCLE

Production of distilled water will not begin until the front drawerpanel 55 of the distiller 15 is closed and the drawer 35 is in its fullysealed position within water heating chamber 31 (the position shown inFIGS. 10 and 19). The upper part of FIG. 36 show two interlock switches330 and 331 that serve this purpose. Switch 330 is set in closedposition when the tray access door at the front of the distiller 15 isclosed. Switch 331 is closed when the drawer 35 is in its fully sealedrelationship within the heating chamber 31.

In the illustrated embodiment (see FIGS. 10 and 19), switch 330 takesthe form of a magnet 131 carried by the drawer panel 55 and anassociated magnetic proximity switch 132 carried on the panel 16 nearthe latch mechanism 63. Switch 331 takes the form of a magnet 133carried on the rear of the drawer 35 and an associated magneticproximity switch 134 carried on the rear wall of the cover 25.

The switches 330 and 331 are connected in series in a circuit thatbegins at a positive DC line 301 and continues to the microcontroller304 by way of a line 333. If either of the interlock switches 330 or 331are open, pin 19 of the microcontroller 304 does not have the positiveDC voltage applied to it, in which case the microcontroller 304 disablesthose functions of the distiller 15 that are necessary for thedistillation of water.

Another necessary condition for activating the distiller 15 is to havethe "RUN" switch 334 closed by manual operation from the front of thedistiller (see FIGS. 4 and 22). This causes a "RUN" LED 135 located onthe front panel 16 (also shown in FIGS. 4 and 22) to turn on, indicatingthat the distiller 15 is ready to begin operation. The LED 135 ispreferably one that emits green light.

Closing the "RUN" switch 334 also connects a line 335 to ground state.The microcontroller 304 is signalled to allowed distiller operation byissuing appropriate commands.

The left region of FIG. 36 shows the three previously described floatoperated reed switches 96, 97, and 98 in the holding tank 30. Theseswitches 96, 97, and 98 are also designated by their circuits in FIG.36, which are respectively marked Switches A, B and C.

In the start up condition, the float 99 is in its lowermost position inthe holding tank 30, because the tank 30 is drained (as FIG. 9A shows).Reed switch 98 (Switch C) is thus closed. The microcontroller 304responds to the closure of Switch C by causing the LED 109 on the faucet22 (see FIG. 5) to turn on adjacent the legend "EMPTY."

The "EMPTY" LED 109 is mounted on a printed circuit board 336, asindicated by a dashed line rectangle marked 336. The LED 109, when on,indicates that the holding tank 30 is empty and that water is notavailable for being drawn out of the faucet 22. The "EMPTY" LED 109 ispreferably red in color.

The previously described LED's 107 and 108 on the faucet 22 (shown inFIG. 5) are also mounted on the circuit board 336. Faucet LED 108preferably emits green light and has the legend "READY" placed next toit. This LED 108 tells the user that the distiller is in condition orready for having water withdrawn from the faucet 22. Faucet LED 107preferably emits yellow light when it is energized and is locatedadjacent the legend "ATTEND." The specific conditions that must be metfor the "ATTEND" and "READY" LED's to turn on will be discussed ingreater detail later.

The microcontroller 304 prohibits the distilled water output pump 89from running when switch C is closed. However, the microcontroller 304will cause line 321 of the heating element switching circuit 314 to goto a low logic level to cause the element 34 to heat up. The sensor 52(also labeled RTD2-HEATER in FIG. 36) monitors the temperature in theregion of the deflected portion 50 of the element 34. RTD2 is symbolizedby a resistor that varies linearly in response to the temperature towhich it is exposed. RTD2 is exposed to the heating element 34 andalways reflects the temperature of the deflected portion 50 of theelement 34.

At this time, the microcontroller 304 will also cause the line of theswitching circuit 315 to go to a logic low level to energize thesolenoid 21 for a brief time (for example, one or two seconds) to bringsome water into the heating chamber 31. The solenoid 21 is then turnedoff while the deflected portion 50 of the element 34 heats to apredetermined high distillation temperature, which in the illustratedembodiment is 110±3° C. The motor for the fan 85 will also be energizedat this time to aid in dispersing the heat radiated from the steamchamber assembly 26.

When the deflected portion 50 of the element 34 reaches thepredetermined distillation temperature, the solenoid 31 opens the raw(undistilled) water infeed valve 37 to begin supplying water to thewater heating chamber 31. The element 34 and the sensor 52 will cool aswater enters the heating chamber 31. When the sensed temperature of thedeflected portion 50 falls to a predetermined intermediate level (whichin the illustrated embodiment is 103±3° C.), the solenoid 31 closes tostop the flow of water into the chamber 31. Should the temperature ofthe deflected portion 50 of the element 34 fall below a predeterminedlow level (which in the illustrated embodiment is 96±3° C.), the element34 is turned on again until the predetermined high distillationtemperature of 110±3° C. is reached. Then, more water is brought intothe heating chamber 31 (by opening solenoid 21).

The above described sequence repeats until the water level in the drawer35 touches the lower surface of the heating element 34. At this time,generation of steam for being condensed into distilled water begins. Thefan 85 continues to draw cooler room temperature air through thecondenser assembly 27 to condense the steam into purified water thatcollects in the holding tank 30.

As the water boils away from the heating element 34 during thedistillation process, sensor 52 (RTD2) senses the rise in temperature atthe deflected portion 50 of the heating element 34. When the temperatureof the deflected portion 50 reaches 110±3° C., the heating element 34 isturned off, and the solenoid 21 controlling the infeed valve 37 isenergized again to bring more water into the chamber 31. As the waterenters the heating chamber 31 (cooling the element 34), the temperaturesensed by RTD2 will reach the predetermined intermediate level (103±3°C.). The solenoid 21 closes.

By sensing the temperature of the element 34 at the deflected portion50, the microcontroller 304 maintains a desired level of water withrespect to the remainder of the element 34. More particularly, the waterin the heating chamber 31 is maintained at a level that is approximatelyone-eighth inch above and below the centerline of the element 34. Thislevel is desirable for the heating element 34 to operate mostefficiently as a film evaporator.

As the temperature of the element 34 drops below the predetermined lowlevel (96±3° C.) during the distillation process, the element 34 isturned on until the predetermined high temperature (110±3° C.) is againattained.

The cycle described in the preceding three paragraphs is repeated duringthe distillation cycle. The distiller 15 will continue to make purifiedwater until the float 99 closes the reed switch 96 (switch A in FIG.36). This position is shown in FIG. 9C. At that time the holding tank 30is full of water. The heating element 34, the solenoid 31, and thecooling fan 85 are turned off. The distillation cycle remains completelyinactive until water is drawn out of the holding tank 30.

During operations to replenish an empty holding tank 30, initiated by aclosing of the reed switch 98 (Switch C), the distillation processproceeds for a specified replenishment period (for example, one hour)before the microcontroller 304 enables the purified water supply pump 89to allow the user to again draw purified water from the holding tank 30upon demand. At this time, the microcontroller activates the "READY" LED108 (green in color) on the faucet 22. A corresponding green lightemitting LED 139 located on the front panel 16 of the distiller 15 willalso be turned on (see FIGS. 4 and 22).

When the float operated reed switch 98 (switch C) is closed because of alow water level in the holding tank 30, the heating element 34 will beinitially operated during the distillation process at a high powercondition (for example, a 500 watt level) to thereby optimize the speedof the distillation process. The water level will rise in the holdingtank 30 as more purified water is distilled. The pump motor 89 will turnon periodically to pressurize the output line 23 to the faucet 22. Thispressure is maintained by the check valve 124.

The accumulation of purified water in the holding tank 30 will cause thefloat 99 to rise until it makes contact with the reed switch 97 (whichis indicated by the letter "B" in FIG. 36). This position is shown inFIG. 9B. The contact closes the reed switch 97 (switch B). This state ofthe switch B is detected by the microcontroller 304 by a line leadingfrom switch B. The microcontroller 304 responds by switching the phaseangle at which the triac 318 for the heating element 34 is triggered sothat the heating element 34 only receives enough current to heat it at areduced power condition (for example, a 250 watt level). At this time,the speed of the condenser fan 84 could also be reduced in view of thereduced heat conditions.

Of course, it should be recognized that the 500 and 250 watt heatinglevels selected in this illustrative embodiment of the invention couldhave other values as well. Concrete numbers are chosen in thedescription to simply illustrate the heating values that have beenchosen in a commercial embodiment of the distiller.

An alternate approach to varying heating element power dissipation caninvolve the use of a probe in the form of a conductivity sensor (notshown) extending into the holding tank 30 from the highest to the lowestexpected water levels in the tank. Essentially, the conductivity sensorcan include two parallel vertically extending conductors that are spacedapart from each other and have an electrical resistance between themthat varies with the extent to which the conductors are immersed inwater. Thus, the resistance varies continuously with changes in thewater level. The microcontroller 304 senses these changes in voltage orcurrent levels and converts the corresponding signals into digital formfor processing. The signals can be used to vary the wattage dissipatedby the heating element on a continuous basis between low and highwattage limits, such that the wattage is increased as the water level inthe holding tank 30 decreases so that distilled water is produced at ahigher rate when the tank 30 is tending towards depletion, and viceversa. The power or wattage supplied to the heating element is caused tovary by phase shifting. Although not shown in the drawings, means areprovided for delivering a signal to the microcontroller 304 indicativeof a zero crossing (that is, crossing of the alternating current waveform between positive and negative) so that time zero is used as areference for establishing the amount of shift of the trigger signalsand, therefore, the amount of power delivered to the heating element.

When water is drawn out of the holding tank 30, the pressure switch 136shown in the far right portion of FIG. 36 closes. This switch 136 closesin response to low pressure and opens when high pressure exists betweenthe check valve 124 and the faucet 22.

The user can continue to draw water from the holding tank 30 until thefloat 99 descends low enough to close reed switch 98 (switch C in FIG.36). When reed switch 97 (switch B in FIG. 36) is closed by thedescending float 99, the distiller 15 will begin to make purified wateragain at the 250 watt power level. When the descending float closes reedswitch 98 (switch C), the unit will revert to making water at the 500watt power level.

B. OVERFLOW SENSOR

There is another float operated switch 136 (switch D in FIG. 36) shownin the drawings. This float switch 136 is installed in a sump 137 (seeFIGS. 3 and 10) formed in the base 24 of the distiller 15. The sump 137collects water that may be the result of a leak in the system oroverflow. The float switch 136 (switch D) is activated in response tooverflow being detected. The switch 136 pulls the line that connects itto the microcontroller 304 pin P7 down to ground level. When thisoccurs, the microcontroller 304 de-energizes the distiller 15 bydisabling the solenoid 21

C. ATTEND WATER FILTER SIGNAL

As mentioned earlier, the faucet 22 includes a filter 105 for adsorbingmaterials that may remain in the distilled water. A signal is derived asa function of the amount of water that is processed by the distiller 15,which, in turn, is a function of the power level and operating time ofthe distiller 15. This signal occurs when a predetermined amount ofwater has been distilled, which indicates that the filter 105 may besaturated with volatiles and replacement is desirable. Themicroprocessor 304 derives the water consumption as a function of timeby counting pulses and accumulating the time and memory. Thepredetermined time will depend upon an empirical determination of theproper time resulting from experience derived with a particular type ofraw water. Once the predetermined time is reached, the microcontroller304 will provide a predetermined water filter "ATTEND" signal.

The water filter "ATTEND" signal is a flash-pause sequential operationof the "ATTEND" LED's 107 and 138. This unique signal continues untilthe RESET switch 337 is pressed again. This turns off the LED's 107 and138 and resets this portion of the memory for beginning to monitor a newusage term of the faucet filter 105.

D. CLEAN TRAY ATTEND SIGNAL

As FIG. 36 shows, the distiller 15 includes a sensor 140 for detectingthe total dissolved solids entering the water heating chamber 31. FIG. 6also shows the sensor 140 in position within the undistilled inlet waterpipe 20 upstream of the valve 37. This sensor 140 is also labeledTDS1-TRAY in FIG. 36. The sensor 140 is symbolized by a variableresistor that varies in response to conductivity of the water enteringthe tray 36. The objective is to cause an indication that the tray 36should be removed for disposal or cleaning.

A unique signal indication of the need for cleaning the tray 36 is used.For example, the need for cleaning the tray 36 may be indicated by the"ATTEND" LED's 107 and 138 being continuously illuminated while underthe control of the microcontroller 304.

The signal indicative that the tray 36 should be cleaned is a functionof the amount of water processed and the total dissolved solids of theincoming water. There are two ways that the tray cleaning signal can bederived. One is to rely upon the amount of water processed. Another wayis to coordinate the amount of water processed with the quality of theraw (undistilled) water based upon the signal derived from the totaldissolved solids sensor 140 (TDS1). The microcontroller 304 can derivethese relationships by coordinating the time during which the element 34is operating at 250 or 500 watts, which is also inherently a function ofrunning time of the unit and the operating power level.

For example, when the distiller is using water that has intermediatemineral content, and has processed approximately 50 gallons of waterwith a total dissolved solids level of about 300 ppm, themicrocontroller 304 will initiate a self cleaning mode (described below)and generate an internal signal to initiate the tray "ATTEND" sequence.In this circumstance, the distiller 15 will continue to make distilledwater until it has filled the holding tank 30 and float operated reedswitch A is closed.

E. SELF-CLEANING MODE

When the distilled water holding tank 30 is filled, as indicated by reedswitch 96 (switch A) closing, the distiller 15 will stop making water.The distiller 15 will automatically enter its previously describedself-cleaning mode. In this mode, the temperature of the heating element34 is allowed to rise to approximately 145° C. (293° F.) as sensed byRTD2 detector. This temperature is sufficient to cause mineral or scalethat has formed on the heating element to crack off and fall into theremovable tray 36. After a predetermined time as measured by themicrocontroller 304, the heating element 34 is turned off. The fan 85stays on for approximately one-half hour to cool down the unit, untilthe RTD2 detects that the temperature of the heater 34 is down toapproximately 45° C. (113° F.). During this time, purified water may bepumped out of the holding tank 30, but the distiller will not beginmaking new water.

After expiration of the time delay, the "ATTEND" LED 107 on the faucet22 (see FIG. 5) will turn on and stay on. Another "ATTEND" LED 138(yellow in color) mounted on the front panel 16 will also turn on (seeFIGS. 4 and 22). When the "ATTEND" LED's 107 and 138 are on, thedistiller 15 is not allowed to make water again until the tray 35 isopened and the reset switch 337 (see FIGS. 4 and 22) is closedmomentarily.

The "ATTEND" LED's 107 and 138 indicate that the user should open thefront drawer 55 and withdraw the tray 36 for cleaning. When the resetbutton is activated, the "ATTEND" LED's 107 and 138 will go out, and thedistiller 15 will be enabled to create steam and make distilled wateragain.

One may see that the DC line voltage plus V is applied from line 301 tothe anodes of the various LED's found on both the PC circuit board 336and the front panel 16. The LED cathodes are attached to ground to turnthem on by the microcontroller pins P24-and P26 switching to a low logiclevel state, which brings about grounding of the return lines 338, 339and 340 by causing the drivers in the interface driver circuit 323 toconnect lines 338, 339 and 340 to ground. Similarly, the red lightemitting LED 109 (that indicates that the holding tank 30 is empty orbelow a level where water is allowed to be drawn from the holding tank30) has a line 340 connected to the LED cathode that is grounded inresponse to pin 23 of the microcontroller 304 switching to a low logiclevel.

F. AIR FILTER ATTEND SIGNAL

The distiller 15 also preferably includes the air filter 141 and an airtemperature sensor 142 in the flow path through the condenser assembly27 (as FIG. 6 shows). The air filter 141 is preferably made of acleanable mesh or foam material and is positioned in the air flowupstream of the condenser assembly 27. The air temperature sensor 142(which is also labeled RTD1 in FIG. 36) is positioned in the air flowpath (as FIG. 6 shows) downstream of the condenser assembly 27.

When the temperature sensed by the sensor 142 is above a predeterminedlevel (for example, about 55±3° C.), the microcontroller 304 willgenerate a specified air filter "ATTEND" flash sequence using the LED's107 and 138. For example, the "ATTEND" LED's 107 and 138 can flash twiceand then pause to indicate that the air filter 141 should be cleaned orreplaced.

The specified air filter "ATTEND" signal is indicative of severalpossible operating conditions. One is that the air filter 141 is soclogged or dirty that it is restricting air flow, therefore raising theair temperature in the flow path. It may also indicate that the incomingroom air is warmer than normal. Warmer incoming room air would requiremore frequent cleaning of the air filter 141 to assure proper coolingwithin the distiller 15. The air filter "ATTEND" signal would also begenerated by the microcontroller 304 if the air fan motor fails orotherwise requires maintenance.

In response to the air filter "ATTEND" signal, the user pushes the "RUN"switch 334 to shut down the distiller 15. After cleaning or replacingthe air filter 141, the user pushes the "RUN" switch 334 again to startthe distiller 15. The user also pushes the "RESET" switch 337 to turnoff the flashing "ATTEND" lights.

Preferably, the microcontroller 304 is programmed to automatically shutdown the distiller 15 whenever the sensor 142 (RTD1) detects aprescribed high level, for example 60±3° C. The distiller 15 willautomatically restart and operate normally when the RTD1 sensor detectsthat the air temperature has dropped below the prescribed high level.

G. CLEAN HOLDING TANK ATTEND SIGNAL

The distiller 15 is also provided with the sensor 95 for continuouslymonitoring the amount of total dissolved solids in the holding tank 30.This sensor 95 is also labeled TDS2-STORAGE in FIG. 36. The probe 95 isa commercially available conductivity sensor that produces an analogsignal depending on conductivity. The signal is delivered to pin 18 ofthe microcontroller 304.

The microcontroller 304 shuts down the distiller and disables thepurified water pump motor 89 whenever the amount of total dissolvedsolids detected by the sensor 95 exceeds a prescribed threshold level interms of parts per million. When this threshold level is exceeded, themicrocontroller 304 also responds by turning off the "READY" green lightemitting LED's 108 and 139. Instead, the microcontroller 304 repeatedlyoperates the "ATTEND" LED's 107 and 138 in a triple flash-pause cycleuntil corrective action is taken.

The analog signal derived from TDS2 is connected to one pin P18 that isin an input to an analog-to-digital converter in the microcontroller304. The signals from TDS1, RTD2, and RTD1 are also analog signals thatare input to pins P15, P16 and P17 of the microcontroller 304, whichare, in turn, input to an analog to digital converter.

The distiller 15 that embodies the features of the invention purifieswater upon demand on a continuous basis. The distiller 15 also monitorsitself on a continuous, real-time basis. Its operation is automatic and,except for periodic maintenance, is independent of any user involvement.

Various features of the invention are set forth in the following claims.

We claim:
 1. A water purification assembly comprisinga cabinet havinginterior walls that define a drawer space having horizontal length andwidth greater than its height, a supply conduit within the cabinet forconveying raw water from a source, a faucet mounted on the cabinet, anda water purification device attached to the supply conduit to receiveraw water, the device including a housing having a horizontal length andwidth greater than its height and dimensioned to fit generally withinand being mounted within the confines of the cabinet drawer space, andoperative means arranged entirely within the length, height and width ofthe housing for purifying the raw water and a conduit connected to saidwater purification device and to said faucet for dispensing the purifiedwater through the faucet.
 2. A water purification assembly according toclaim 1wherein the water purification device includes means within thehousing for circulating air about the operative purification means, andwherein the cabinet includes a face panel on the front of the drawerspace that includes at least one air intake vent for conducting air intothe drawer space to the circulating air means and at least one airouttake vent for conducting air from the drawer space from thecirculating air means.
 3. A water purification assembly according toclaim 1wherein the operative purification means purifies the raw waterby distillation and includes a steam chamber that receives raw water andconverts it to steam, a condenser that condenses the steam to distilledwater, and air circulation means for drawing cooling air through thecondenser, the steam chamber, condenser and air circulation means beingarranged generally spaced apart horizontally relative to each otherentirely within the height of the housing, and wherein the cabinetincludes a face panel on the front of the drawer space that includes atleast one air intake vent for conducting air into the drawer space tothe air circulation means and at least one air outtake vent forconducting air from the drawer space form the air circulation means. 4.A water purification assembly according to claim 1wherein the waterpurification device includes an access drawer on the housing that opensto allow access to the operative purification means and that closes toprevent such access, and wherein the access drawer is exposed throughthe front portion of the cabinet drawer space for manipulation by theuser.